| Adjusting Valves |
|
Car Words A valve is an engine component that opens and closes to control the flow of liquid, gas, or vacuum. Most commonly, the intake valve(s) lets the fuel-air mixture into the engine and the exhaust valve(s) lets combusted gases out of the engine. Smaller engines have more than one of each valve in a cylinder to save room in the cylinder head. As an overview, here’s how valves are adjusted on modern cars. Remember that the valve’s job is to open and close at exactly the perfect moment so that fuel comes in or exhaust exits the cylinder as designed. A critical component called the camshaft actually does the timing. What you’ll be adjusting is the lash or opening between parts. 1. Remove the engine’s valve cover (this may require moving some other components depending on the car’s design). 2. Rotate the engine until the TDC (top-dead-center) mark is under the pointer at the crankshaft pulley. 3. Use a valve feeler gauge to measure the distance between the rocker and valve tip. If the distance is not as recommended by the car’s manufacturer, loosen or tighten the adjustment nut as needed. 4. Perform the measurement and adjustment for each valve on the engine. Note that intake and exhaust valves have different distances or clearances. In addition, some engines have more than one intake or exhaust valve. Please don’t try to adjust your car’s valves from this overview. It is intended solely as an overview to the process. Actual instructions (in a service manual) are more specific to your car’s requirements.
|
Here’s where many do-it-yourselfers hire a mechanic. Why? Because valves are very sensitive to adjustment. Improper adjustment can dramatically change your gas mileage—or damage the engine. However, the job itself isn’t that difficult. So if you’re mechanically inclined and want to save quite a few bucks, invest in a shop manual for your model car and have at it.
